Mixtures of mono-n-alkylbenzenes and di-n-alkylbenzenes

ABSTRACT

LUBRICANT OILS COMPRISING 5-30 PARTS BY VOOLUME OF MONO-N-ALKYLBENZENES AND 70-95 PARTS BY VOLUME OF DI-N-ALKYLBENZENES.

United States Patent Office 3,725,280 Patented Apr. 3, 1973 No Drawing.Continuation of abandoned application Ser.

No. 725,908, May 1, 1968. This application May 10, 1971, Ser. No.148,266

Int. Cl. C10m 1/16 U.S. Cl. 252--59 13 Claims ABSTRACT OF THE DISCLOSURELubricant oils comprising -30 parts by volume of mono-n-alkylbenzenesand 70-95 parts by volume of di-n-alkylbenzenes.

CROSS-REFERENCE STATEMENT This application is a streamlined continuationof abandoned application Ser. No. 725,908, filed May 1, 1968.

BACKGROUND The present invention relates to synthetic hydrocarboncompositions having properties which render them particularly useful aslubricants in extremely low temperature operations.

Various petroleum fractions have been used as lubricants for many years.While the petroleum-derived lubricants have been satisfactory for mostuses, there are fields of use, as for example, jet engine lubricants andarctic oils, wherein the requirements render the conventionalpetroleum-derived lubricants either unsatisfactory or of marginalutility. In an attempt to solve this problem synthetic lubricants (forexample, diesters) have been developed having improved properties,particularly improved viscosity and pour point properties.Unfortunately, however, the synthetic lubricants of the prior art havebeen relatively expensive. It is thus apparent that it would be highlydesirable to develop an inexpensive synthetic lubricant having very goodviscosity, pour point and flash point properties.

PRIOR ART The following US. patents are believed to be the mostpertinent prior art.

US. 3,288,716, to Becraft and Durr, teaches a synthetic hydrocarbonlubricant having good low temperature viscosity, excellent pour pointand flash point properties. The composition of this patent contains thefollowing materials: dialkylbenzenes; diphenylalkanes; alkyl tetralins,indanes, and other condensed alkyl aromatics; and, monoalkylbenzenes.The patent teaches (1) preferably, the diphenylalkanes are present inamounts of about 5 parts to about 50 parts by volume and (2) themonoalkylbenzenes are not desirable.

U.S. 3,173,965, to Pappas and Kant, teaches dialkylbenzenes aslubricants. The patent does not recognize that addition ofmonoalkylbenzenes to dialkylbenzenes can improve the physical propertiesof the product mixture. The patent teaches that the dialkylbenzenes areprepared by: (1) alkylating benzene with an alkylating agent and (2)alkylating the resulting monoalklybenzene with an alkylating agent. Thepatent further teaches that the alkylating agent can be a-olefins,monohydroxylated paraflins, or monohalogenated paraffins, and, in thisconnection states: Alkylation as used herein means a process forintroducing alkyl substituents onto a benzene residue in which thelinkage is through the a-carbon atom of the alkyl substituent.

It may be well to state at this: time that the hydrocarbon compositionsof our invention are restricted to di-n-alkylbenzenes derived bydisproportionation of monon-alkylbenzenes. We have found that productsprepared by disproportionation give the best compromise of lowtemperature pour point and low temperature viscosity in the product. Bycontrast, use of alkylation to introduce the second alkyl group onto thebenzene ring improves the viscosity property but deteriorates the pourpoint.

BRIEF SUMMARY OF THE INVENTION Broadly stated, our invention relates tosynthetic hydrocarbon lubricating compositions consisting essentially offrom about to about parts by volume of a disproportionated productderived from mono-n-alkylbenzenes, which are predominantlydi-n-alkylbenzenes, and from about 5 to about 30 parts by volumemono-n-alkylbenzenes, the alkyl groups of said mono-n-alkylbenzenes andsaid di-n-alkylbenzenes containing from 10 to 15 carbon atoms,preferably from 12 to 14 carbon atoms, said compositions containing lessthan 4.5 percent, preferably less than 2 percent, by volume,diphenylalkanes.

The disproportionated products, which are derived frommono-n-alkylbenzenes, are sometimes referred to simply asdi-n-alkylbenzenes, hereinafter.

In one aspect our invention relates to a method of lubrication employingas the lubricant the synthetic hydrocarbon compositions described in theforegoing. In particular this aspect relates to the lubrication ofmachinery and turbojet engines employing the synthetic hydrocarboncomposition described in the foregoing.

It should be emphasized that the synthetic hydrocarbon lubricatingcompositions described in the foregoing in addition to having a specificchemical composition must meet certain specific physical propertiesdescribed hereinafter.

DETAILED DESCRIPTION Description of desired physical propertiesMIL-L-IOZQSA SPECIFICATION S Requirement limits Physical propertyMinimum Maximum Viscosity, kinematic, cs.:

at 210 F Pour point, F Stable pour point, F Flash point, 00 0, F-

The requirements for a grade of oil suitable for use in jet aircraftengines for type 11 service are stated in military specification,MIL-L-23699A, which is listed below.

MIIF'IIZBGQQA. SPE GIFIOATION S Requirement limits Physical propertyMinimum Maximum The lubricant compositions of our invention meet one orboth of the specifications stated above. Due to the variation of thephysical requirements of the two specifications, it is extremelydifficult for a lubricant composition to meet both specifications. Someof our composi tions meet both requirements. Generally, it is better toprepare a composition which meets only one of the specifications. Someof our compositions meet a single specification as stated above. It iswithin the scope of our invention to provide a composition which meetseither of the specifications. Knowing the specification and having ourinvention before him any person skilled in this art can arrive at acomposition which meets either specification.

While the lubricant compositions of our invention are effective aslubricants, it is customary in this art to incorporate in the lubricantvarious additives, such as oxidation inhibitors, corrosion inhibitors,anti-foam agents, and viscosity index improvers. For this reason, theterm lubricant composition as used herein means a base lubricantcomposition, and not a compounded lubricant composition.

While the physical property requirements stated in MIL- L-10295A andMIL-L-23699A define absolute limits for the fully additive-compoundedlubricant, rather than the base oil, our lubricant compositions meetthese requirements, within the limits defined in the foregoing.

It has been our observation that the use of additives has an adverseeffect on the physical properties, particularly viscosity properties, ofthe compounded lubricant. For this reason, it is preferable that thebase lubricant, to be used in an arctic oil, have the followingviscosity properties.

Viscosity, cs.: at 210 F.: minimum, 4.10; at 40 F.: maximum, 6,500.

A lubricant composition of our invention for use as an arctic oil,suitably, meets the MIL-L-10295A specification stated previously and,preferably, has the following more stringent viscosity properties:

Viscosity, cs. at 210 F.: 4.50 minimum; at -40 F.: 6,000 maximum.

Preparation of our compositions As stated previously, the compositionsof our invention consist essentially of mixtures ofmono-n-alkyl-benzenes and disproportionated products which arepredominantly di-n-alkylbenzenes. Prior to describing in detail thesematerials, We believe it may be well at this time to describe thepreferred method of preparing them.

Preferably, the mixture of mono-n-alkylbenzenes is prepared byalkylating benzene with a mixture of substantially monohalogenatedparaffins, containing to carbon atoms, using a Friedel-Crafts catalyst.One such method is described in detail in US. Pat. No. 3,316,294 whichis made a part of this disclosure.

Briefly, US. 3,316,294 relates to a process of preparing a detergentalkylate, wherein the process comprises the following steps, broadlystated: (a) separating a fraction of substantially straight-chain (l -Chydrocarbons from a petroleum distillate substantially free of olefinsand containing said straight-chain hydrocarbons together withnon-straight chain hydrocarbons, (b) chlorinating said fraction to theextent whereby between about 10 and about 35 mole percent of thestraight-chain hydrocarbons present are substantially onlymono-chlorinated, and (c) alkylating an aromatic compound, e.g. benzene,with the chlorination product of step (b) in the presence of analkylation catalyst.

While US. 3,316,294 concerns a process which can use C to C hydrocarbonsthe present invention uses, at the most, hydrocarbons containing from 10to 15 carbon atoms. This selection of 10 to 15 carbon atoms can be madeeither in the initial feedstock or by fractionation of the alkylbenzeneproduct.

The mixture of mono-n-alkylbenzenes which is used per se in ourlubricant compositions, and also to prepare the disproportionatedproducts, has the following properties:

Suitable Preferred Preparation of disproportionated product Thedisproportionated product is derived from the above-describedmono-n-alkylbenzenes. As a starting material for the disproportionationreaction we can use the entire mono-n-alkylbenzene fraction. Also, Wecan distill overhead selected amounts of the mono-n-alkylbenzene and usethe overhead fraction. Further, we can subject the mono-n-alkyl-benzeneto fractional distillation and use selected fractions.

Process conditions for disproportionation reaction Disproportionation ofthe mono-n-alkylbenzenes to di-n-alkylbenzenes is conducted using aFriedel-Crafts catalyst. The term Friedel-Crafts catalyst is wellunderstood in the art and refers, generally, to materials such as thealuminum halides, boron trifluoride, boron trichloride, antimonychlorides, stannic chloride, zinc chloride, and mercuric chloride.Preferably, the Friedel-Crafts catalyst is aluminum chloride or aluminumbromide. The more preferred catalyst is aluminum chloride, which alsoincludes in situ prepared aluminum chloride, or, in other words, thereaction product of aluminum metal and hydrogen chloride.

In some cases it is desirable to use a proton-donor promoter with theFriedel-Crafts catalyst. Suitable promoters include any material which,when added to the catalyst, yields a proton. Preferred promoters arehydrogen chloride and water. The amount of promoter is typically about 4weight percent based on the weight of the catalyst employed.

Preferably, the catalyst is added to the reaction mixture after themono-n-alkylbenzenes are brought to within the correct temperaturerange, which will be described below. The amount of the catalyst whichis used can vary from about 0.1 weight percent to about 10 weightpercent based on the mono-n-alkylbenzene starting material. Preferably,the amount of catalyst is from about 0.5 weight percent to about 3weight percent.

The disproportionation process, suitably, is conducted at a temperatureof from about 20 C. to about 130 C. Since maximum yields of thedi-n-alkylbenzenes are obtained at temperatures between about 75 C. and120 C., these temperatures are preferred. The most preferred temperatureis about 100 C. When this temperature is used, preferably the amount ofcatalyst is from about 1 to about 2 weight percent.

Following the reaction, the reaction mass is distilled in order toremove the benzene, paraflins and unreacted mono n alkylbenzenes. Thedesired disproportionation product is the bottoms fraction with adistillation cut point of 197 C. at 5 mm. Hg. In other words the desiredproduct distills above 197 C. at 5 mm. Hg.

While We have described in detail the process conditions for thedisproportionation reaction, the disproportionation process is not partof our invention. This process is disclosed and claimed in applicationSer. No. 529,- 284, filed Feb. 23, 1966, and now abandoned.

Description of mono-n-alkylbenzenes and di-n-alkylbenzenes Preferably,the mono-n-alkylbenzenes used in our invention, have a composition whichcan be represented by the following formula:

where R; is a straight-chain alkyl group containing 1 to 7 carbon atomsand R is a straight-chain alkyl group containing 1 to 8 carbon atoms,with the sum of R and R being from 9 to 14.

The mono-n-alkylbenzene mixture used in the final composition has aviscosity index (100-210 F. basis) of from about 75 to about 90, and apour point of from about 70 F. to about 115 F.

The di-n-alkylbenzenes present in the disproportionated product used inour invention have alkyl groups of the same type as themono-n-alkylbenzenes described in the foregoing. The disproportionatedproduct used in the final composition has a viscosity index (100210 F.basis) of from about 105 to about 120 and a pour point of from about -55to about 70 F. The disproportionated product contains at least 55percent by weight di-n-alkylbenzenes, preferably at least 70 percent byweight di-n-alkylbenzenes.

The lubricating compositions of our invention contain the followingamounts of mono-n-alkylbenzenes and disproportionated product (in partsby volume).

USES FOR OUR COMPOSITIONS The lubricant compositions of our inventionare partic ularly useful wherever a combination of low pour point (eg 65F.) and good viscosity properties at -40 F., F and 210 F. are needed. Asstated previously they are particularly useful for lubricating machinery(internal combustion engines or otherwise) in arctic climates. They arealso particularly useful as jet engine lubricants. They can be used inautomatic transmission fluids and in hydraulic fluids. Their propertiesrender them useful in a wide variety of specialized lubricationproblems, an example of which is the lubrication of aircraftinstruments. Moreover, they can be used as base lubricants in thepreparation of specialty greases.

In order to disclose the nature of the present invention still moreclearly, the following illustrative examples will be given. It is to beunderstood that the invention is not to be limited to the specificconditions or details set forth in these examples except insofar as suchlimitations are specified in the appended claims.

EXAMPLE 1 This example shows the preparation of a pilot plant batch ofthe lubricant of our invention.

DISPROPORTIONATION Two batches of disproportionate were prepared.

RUN A The charge was an alkylate fraction prepared by the process of US.3,316,294. The alkylate fraction had the following composition andproperties:

Mono-n-alkylbenzenes: Wt. percent C10 and C11 C 12.5 C 44.3 C 32.2

Wt. Percent Dialkyltetrahydronaphthalenes 8.0 Miscellaneous compounds1.0

Molecular weight, 260. Boiling range, at 5 mm. Hg, -197 C.

Procedure To a SOO-gallon Pfaudler vessel were charged 2375 lbs. of theabove-described alkylate. While stirring and heating the alkylate to 100C., HCl was added until the alkylate was saturated. HCl addition wasthen stopped. A weight of 19 lbs. of anhydrous AlCl was added to themixture as catalyst. The reaction mass was mixed at 100 C. for 1 hourfollowing the catalyst addition. Mixing was stopped and the reactionmass was settled for about 2 hours. Spent catalyst sludge (43 lbs.) wasre moved and the remaining product was caustic washed (5% caustic) andwater washed using about /2 volume of Wash solution per volume ofreaction mixture. The washed product Weighed 2299 lbs. GLC (gas-liquidchromatography) analysis showed about 5.7% benzene, 5.6% paraflins,66.2% monoalkvlbenzene and 22.5% bottoms.

RUN B Procedure The procedure was similar to that of Run A; there wereused 2381 lbs. of the alkylate described in Run A and 20 lbs. AlClcatalyst. The residence time for the reaction was 1 /2 hours. There wererecovered from the reaction 2329 lbs. of washed product and 44 lbs. ofspent sludge. GLC analysis of the product showed 6.5% benzene, 5.9%parafiin, 63.0% monoalkylate and 24.6% bottoms.

7 FRACTIONATION The products from Runs A and B were commingled anddistilled in two batches in ll-barrel stills. Combined data on thecharge and the fractions are shown below.

Temp. range,

General F. (corrccted Weight Fraction identification to 760 mm. Hg)(lbs.)

Charge Crude dispropor- 4,560

tionate.

Benzene IBP(l46)-194 217 Out #2 Paratlins IBP(l46)-55O 226 Out #3Monoalkylbenzenes. 700 2,628 Bottoms Dialkylbenzones 700 1, 452 Percentrecovery 97. 9

FORMULATION BLENDING Monoalkylbenzenes (-15 fraction) 767Dialkylbenzenes (16-66 fraction) 8991 Blend 5981 The physical propertieson the blend were as follows:

Viscosity at 210 F., cs. 4.23 Viscosity at 100 F., cs. 22.75 Viscosityat 40 F., cs. 5981 Flash, COC, F. 400

Pour point, F. *75

*And still flowing.

Blend 6333P was used as a base lubricant for an automatic transmissionfluid test.

Fractions from the remaining three SO-gallon still distillations wereblended to obtain a second blend, which was designated -6475P. The tablebelow shows the origin and characteristics of this blend.

Volume percent Weight, Viscosity at Fraction overhead lbs. 40 F., cs.

Cut 1, disproportionate 5, 841 Outs 2 thru 10, disproportionate 584-221-67 62.0 8, 394

Out 1 disproportionate 6, 077 Cuts 2 thru 10, disproportionate 584-421-66 97.0 8, 962

Cuts 1 thru 7, disproportionate 584-5 0-14 28- 5, 547 Cuts 8 thru 19,disproportionate 584-5 -66 180.0

Total, ca 13%- 87% 39. 29 5, 642

IMAB; DAB.

Blend 6475P'had the following physical properties:

Gravity, API 32.1 Viscosity, at 210 F., cs. 4.19 Viscosity, at 100 F.,cs. 22.22 Viscosity, at -40 F., cs. 5642 Viscosity index 100 Flashpoint, COC, F. 400

Pour point, F. (below) 80 EXAMPLE 2 Blend 633 3P was used as a baselubricant for an automatic transmission fluid. The compounded lubricanthad the following composition:

Wt. percent 6333P 92.75 Dispersant-inhibitor 1.5 Dispersant-antirust 2.0Antiwear oxidation inhibitor 1.0 Antiwear additive 0.75 V.I. improver2.0

The test was a standard Power Glide transmission test. Duration of thetest was 300 hours. The results of the test were as follows:

Varnish l Sludge 1 1. Oil seals: Front seal flexible, no cracking.

Other seals flexible with some cracking. 2. Composition clutch plates:

A. Drive unit, normal, no chipping of composition B. Reverse unit,normal, no chipping of composition 3. Steel clutch plates:

A. Drive unit.

B. Reverse unit 4. Clutch piston-inside 5. Servo interior: A. Piston..B. Cover Pressure regulator valve Oil screen metal side. 8. Oil panTotal rating Average 1 Best possible rating is 10.

EXAMPLE 3 Blend 6475P was used as a base lubricant for a test in a 1-HCaterpillar engine. The compounded lubricant had the followingcomposition:

Wt. percent 6475P 91.00 Dispersant-inhibitor 1.5 Dispersant-antirust 2.5Antiwear oxidation inhibitor 2.25 V.I. improver 2.0 Antiwear additive0.75

The compounded lubricant was tested for 480 hours in the Caterpillarengine.

The following examples illustrate the physical properties obtained byblending different ratios of monoalkylbenzenes and dialkylbenzenes. Inall examples the monoalkylbenzenes were prepared by the preferredprocess described herein; the dialkylbenzenes were prepared bydisproportionation of monoalkylbenzenes.

EXAMPLES 4-6 Ex. 4 Ex. 5 Ex. 6

Physical properties MAB DAB blend blend blend Viscosity at- 100 F., cs-33.0 23.10 22. 13 21. 24

210 F., cs. 5. 64 4. 39 4. 25 4. 14

Pour point, F 50 55 60 65 9 EXAMPLE 7 I This example shows the effect on40 F. viscosity of a blend containing 25% monoalkylbenzenes and 75%dialkylbenzenes. The physical properties were as follows:

MAB DAB blend EXAMPLE 8 This example shows the properties of a blendcontaining 91% dialkylbenzenes and 9% monoalkylbenzenes.

The physical properties were as follows:

Physical properties MAB DAB blend Viscosity at- 40 F., cs 498 8, 036 5,902

100 F., cs 27. 84 23. 81

Pour point, F --75 80 The chemical composition of the monoalkylbenzenefraction, the dialkylbenzene fraction and the blend was as follows(based on mass spectrometer analysisby Z No. Identification).

This example shows the properties of a blend containing 88%dialkylbenzenes and 12% monoalkylbenzenes.

The physical properties were as follows:

Physical properties MAB DAB blend Viscosity at Pour point, I -110 70 -75The chemical composition of the materials was as follows (based on massspectrometer ana1ysis-Z No. Identification).

[Mass Spec. (by Z No. Identification)] Compound types volume percent ZNo. Identification MAB DAB Blend Dihydronaphthaleues 1. 9 3. 4 3.2 8--Tetr 18. 5 16. 0 15.7 -6 Alkylbenzenes... 84.3 76. 4 77. 3 Anthracenes0. 2 O. 2 0.1 0.1 2.0 1.8 I 1. 8 1. 6

Total 100.0 99. 9 99. 9

While particular embodiments of the invention have been described, itwill be understood, of course, that the invention is not limitedthereto, since many modifications may be made; and it is, therefore,contemplated to cover by the appended claims any such modifications asfall within the true spirit and scope of the invention.

The invention having been described, what is claimed and desired to besecured by Letters Patent is:

1. A synthetic hydrocarbon lubricating composition consistingessentially of from about 70 to about parts by volume ofdisproportionated product, said disproportionated product comprising atleast 55 percent by weight di-n-C -C -alkylbenzenes and being preparedby (1) contacting mono-n-C C -alkylbenzenes with a Friedel- Craftscatalyst at a temperature of from about 20 C. to about 130 C. and (2)recovering from the reaction product the disproportionated productfraction, and about 5 to about 30 parts by volume mono-n-C -C-alkylbenzenes, said lubricating composition containing less than about4.5 volume percent diphenylalkanes and being characterized further ashaving the following physical prop erties:

Viscosity, cs. at 210 F.: At least 4.00

Viscosity, cs. at 40 F.: Not more than 13,000

Flash point, COC, F.: Above 290 Pour point, F.: Below -50 2. Thehydrocarbon lubricating composition of claim 1 wherein (1) theFriedel-Crafts catalyst used to prepare the disproportionated product isselected from the group consisting of aluminum chloride and aluminumbromide and (2) the cut-point for recovering the disproportionatedproduct from the reaction product is about 197 C. at 5 mm. Hg pressure.

3. The hydrocarbon lubricating composition of claim 2 wherein theFriedel-Crafts catalyst is aluminum chloride.

4. The hydrocarbon lubricating composition of claim 3 characterizedfurther in that it consists essentially of from about 78 to about 92parts by volume disproportionated product and from about 8 to about 22parts by volume mono-n-alkylbenzenes.

5. The hydrocarbon lubricating composition of claim 4 characterizedfurther in that it contains less than 2 volume percent diphenylalkanes.

6. The hydrocarbon lubricating composition of claim 5 characterizedfurther in that it has a pour point of below -'65 F.

7. The hydrocarbon lubricating composition of claim 5 characterizedfurther in that it has a flash point of above 450 F.

8. The hydrocarbon lubricating composition of claim 6 characterizedfurther in that substantially all of the alkyl groups in both thedi-n-alkylbenzenes and mono-nalkylbenzenes contain from 12 to 14 carbonatoms.

9. The hydrocarbon lubricating composition of claim 7 characterizedfurther in that substantially all of the alkyl groups in both thedi-n-alkylbenzenes and mono-nalkylbenzenes contain from 12 to 14 carbonatoms.

10. The hydrocarbon lubricating composition of claim 8 characterizedfurther in that it consists essentially of from about 82 to about '90parts by volume disproportionated product and from about 10 to about 18parts by volume mono-n-alkylbenzenes.

11. The hydrocarbon lubricating composition of claim 9 characterizedfurther in that it consists essentially of from about 82 to about 90parts by volume disproportionated product and from about 10 to about 18parts by volume monon-alkylbenzenes.

12. A synthetic hydrocarbon lubricating composition consistingessentially of about 13 parts by volume monon-C C -alkylbenzenes andabout 87 parts by volume of disproportionated product, saiddisproportionated product comprising at least 70 percent by weightdi-n-'C -C alkylbenzenes and being prepared by (1) contacting mono-n-C-C -alkylbenzenes with a catalyst selected from the group consisting ofaluminum chloride and alurninum bromide at a temperature of from about75 C. to about C. and (2) recovering from the reaction products thefraction distilling above about 197 C. at 5 mm. Hg pressure, saidlubricating composition containing less than about 4.5 volume percentdiphenylalkanes and being characterized further as having the followingphysical properties:

Viscosity, at 210 F., cs.: About 4.23

Viscosity, at 100 F., cs.: About 22.75

Viscosity, at 40 F., cs.: About 5981 Flash point, COC, F.: About 400'Pour point, B: At least about 75.

13. The hydrocarbon lubricating composition of claim 12 wherein thecatalyst used to prepare the disproportionated product is aluminumchloride.

DANIEL E.

12 References Cited UNITED STATES PATENTS WYMAN, Primary Examiner I.VAUGHN, Assistant Examiner US. Cl. X.R.

